1. Field of the Invention
The invention relates to a method for transporting substrates, to a load port apparatus, and to a substrate transport system.
Specific applications of the invention relate to the use and structure of a substrate transport method and those of a substrate transport system, which transports substrates container to contain substrates.
2. Background Art
The invention relates to, as a typical example, an airtight substrate container for housing and transporting substrates at the time of manufacture of a semiconductor device or liquid-crystal display device, as well as to a load port apparatus for taking the substrates housed in the substrate container into a substrate processing system. The invention will be described hereinbelow by means of taking manufacture of a semiconductor device as an example.
FIG. 8 is a perspective view for describing a known side-door-integral-type substrate container to be used for manufacture of a semiconductor device.
This container is listed in, e.g., a catalogue of FLUOROWARE Co., Ltd. A substrate container of this type is called a FOUP according to the SEMI standards. Here, the word xe2x80x9cFOUPxe2x80x9d is an abbreviation of xe2x80x9cfront opening unified pod.xe2x80x9d Information about detailed dimensions of the FOUP is provided in e.g. E62, E1.9 and E47.1 of the SEMI standards.
Reference numeral 100 shown in FIG. 8 designates a wafer carrier serving as a substrate container. Here, the wafer carrier is described by reference to a FOUP standardized by the SEMI standards. As shown in FIG. 8, reference numeral 2 designates a carrier door whose surface is partially cut away.
Here, the wafer carrier 100 has a carrier shell 1 and the carrier door 2. Boards can be loaded or unloaded by way of the carrier door 2 into the wafer carrier 100.
In the wafer carrier 100, substrates are supported by wafer teeth 10 provided inside a carrier shell 1 and by retainers 11 provided on the carrier door 2.
In a state in which the carrier door 2 is closed, the inside of the wafer carrier 100 is a sealed space, and substrates are protected from extraneous matter in the atmosphere or chemical contamination.
Transporting substrates to a substrate processing system where the substrates are to be subjected to required processing requires a load port apparatus having a mechanism for unloading substrates stored in the wafer carrier 100 and taking the substrates into the substrate processing system. For instance, the FOUP corresponds to a load port apparatus having an FIMS surface standardized by the SEMI standards.
The word xe2x80x9cFIMSxe2x80x9d is an abbreviation of xe2x80x9cfront-opening interface mechanical standard.xe2x80x9d
FIG. 9 is a schematic cross-sectional view showing a load port apparatus 300 provided in the substrate processing system when the wafer carrier 100 is placed on the load port apparatus 300.
The load port apparatus 300 has kinematic pins 31A to be used for placing the wafer carrier 100 at a given position on a table section 30 of the load port apparatus; and a load port door (FIMS door) 32 which performs opening and closing actions upon docking with the carrier door 2.
In this system, after the wafer carrier 100 housing substrates 19 has been placed on the load port apparatus 300, the load port door (FIMS door) 32 docks with the carrier door 2 of the wafer carrier 100, thereby opening the carrier door 2. At this time, the load port door 32 and the carrier door 2 that have docked with each other are stored at a predetermined location within the substrate processing system.
In such a system, when the carrier door 2 is opened or closed, external air enters the wafer carrier 100. At this time, extraneous matter or the like also enters the wafer carrier 100 while being mixed with the external air and adheres to the substrates stored in the wafer carrier 100. Adhesion of such extraneous matter potentially induces pattern failures or the like, and hence countermeasures against the extraneous matter must be taken in some way.
To this end, the load port apparatus is dimensionally designed and centered such that compatibility regarding dimensional accuracy and clearance is maintained among all FOUPs without involvement of a problem. There is prevented occurrence of extraneous matter, which would otherwise be caused by longitudinal, horizontal, or vertical offsets of the wafer carrier.
Gentle opening and closing of a door is implemented by means of lowering opening and closing speeds of a door or changing the speed or acceleration of the door at the time of opening the door. Alternatively, gentle opening and closing of the door is embodied by use of cams or springs. These measures prevent flow, into the wafer carrier, of external air including extraneous matter, which would otherwise be caused by friction of a packing or door.
In one type of load port apparatus, a movable section is changed from an upper location to a lower location for preventing adhesion of extraneous matter to the substrates even when the extraneous matter has developed from a movable section for detecting presence/absence of substrates or measuring the heights of substrates, such as a mapper.
A certain substrate processing system is constructed such that the inside of the system is maintained at a pressure higher than the pressure of the outside air, whereby the load port apparatus can effect blowout incessantly. Even if slight influx has developed, influx of outside air into the wafer carrier is prevented.
A carrier door of the wafer carrier is opened or closed by means of pulling away or pressing. The opening and closing actions of the carrier door will now be described by reference to FIGS. 10A through 10D.
FIGS. 10A to 10D are views showing the opening or closing states of the wafer carrier door. FIGS. 10A and 10B are views showing a state in which the carrier door is closed. FIGS. 10C and 10D are views showing a state in which the carrier door is opened.
As shown in FIG. 10A, when the carrier door 2 is closed, the carrier door 2 is pushed in the direction of the arrow. A narrow clearance is usually present between the carrier door 2 and a portion 1A of the carrier shell 1 opposing the same. Hence, when the carrier door 2 has started closing, an internal atmosphere of the wafer carrier 100 encounters difficulty in escaping outside. Accordingly, the inside of the wafer carrier 100 is pressurized by means of only an amount corresponding to the volume of the thus-pushed carrier door 2.
As shown in FIG. 10B, measures for releasing an internal atmosphere of the wafer carrier 100 to the outside can be taken by means of arranging the carrier shell so that the portion 1A of the carrier shell 1 opposing the carrier door 2 can be opened outside when the carrier door 2 is pushed. By means of the measures, even when extraneous matter has developed at the time of closing of the carrier door, the extraneous matter is carried by the flow of the atmosphere escaping from the inside of the carrier to the outside, thus preventing entry of the extraneous matter into the wafer carrier.
As shown in FIG. 10C, when the carrier door 2 is opened, the carrier door 2 is pulled away in the direction of the arrow. Even in this case, the clearance between the portion 1A of the carrier shell 1 and the carrier door 2 is usually narrow. Hence, the inside of the wafer carrier 100 is depressurized by only an amount corresponding to the volume of a withdrawn carrier door 2.
In this case, since the outside air has a positive pressure as compared with the depressurized inside of the carrier, the outside air can flow into the wafer carrier 100, as indicated by the arrows shown in FIG. 10D. For example, as shown in FIG. 10D, if extraneous matter has developed as a result of slight offset of the carrier door 2, the extraneous matter flows into the wafer carrier 100 while being carried by the flow into the wafer carrier 100. If the extraneous matter that has entered the wafer carrier 100 adheres to the substrates 19, a problem of occurrence of pattern failures will arise. Therefore, countermeasures against the problem must be taken in some way.
As has been described, when the carrier door of the wafer carrier is opened, the inside of the wafer carrier is depressurized by only an amount corresponding to the volume of the door to be pulled away, whereupon the outside air flows into the wafer carrier. If extraneous matter has developed in a sealing portion or a door of the wafer carrier by means of friction, the extraneous matter will enter the wafer carrier while being carried by the flow of outside air into the wafer carrier and adhere to substrates.
The invention aims at preventing entry of extraneous matter into a wafer carrier and proposes substrate transport means which prevents occurrence of a phenomenon of outside air flowing into a wafer carrier. This means enables a reduction in faulty products, such as imperfect products, and achievement of high production yield.
According to one aspect of the present invention, in a method of transporting substrates, a substrate container having substrates stored therein and sealed with a door is placed on a load port apparatus provided on a substrate processing system. A door of the load port apparatus is docked with the door of the substrate container. After an inside of the substrate container is pressurized, the door of the substrate container is opened. The substrates stored in the substrate container is transported to the substrate processing system.
In another aspect of the present invention, a load port apparatus comprises a table section which is provided in a substrate processing system and on which is placed a substrate container, and a mechanism for opening a door of the substrate container and transporting substrates stored in the substrate container to an inside of the substrate processing system. The load port apparatus further comprises gas supply means for supplying pressurized gas into the substrate container by way of a gas flow channel provided in the substrate container.
In another aspect of the present invention, a substrate transport system comprises a gas flow channel, a substrate container having a reclosable door, and a load port apparatus. The load port apparatus includes gas supply means, the means being provided in a substrate processing system and supplying pressurized gas. When the substrate container is placed on the load port apparatus, when a door of the substrate container is caused to dock with a door of the load port, and when the door of the substrate container is opened, to thereby transport substrates stored in the substrate container to an inside of the substrate processing system, the gas supply means of the load port apparatus can supply pressurized gas to an inside of the substrate container by way of the gas flow channel of the substrate container.
Other and further objects, features and advantages of the invention will appear more fully from the following description.